Synthesis of [3.4]‐Spirooxindoles through Cascade Carbopalladation of Skipped Dienes

A synthetic route to [3.4]‐spirooxindoles based on cascade carbopalladation reactions of 1,4‐dienes is described. While carbopalladation of alkenes have been used to access mainly [4.4]‐ or [4.5]‐spirocycles, 4‐exo‐trig carbopalladation has not been yet applied to the synthesis of relevant [3.4]‐spirooxindole scaffolds bearing a cyclobutyl ring. In addition, the cascade reaction generates an exocyclic double bond that can serve as a platform to further diversify the substitution pattern of the spirooxindole nuclei.